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United States Patent | 5,587,683 |
Kawasaki ,   et al. | December 24, 1996 |
A booster circuit device comprises: a liquid crystal drive circuit (14) whose dissipated current changes; a timing circuit (11) for outputting a select signal according to the dissipated current of the liquid crystal drive circuit; a drive signal select circuit (12) for selecting and outputting any one of at least two drive signals CLK of different frequencies on the basis of the select signal outputted by the timing circuit (11); and a booster circuit (13) for supplying a supply voltage to the liquid crystal drive circuit (14) on the basis of the drive signal CLK outputted by the drive signal select circuit (12). Since any of the drive signals CLK of different frequencies can be selected and applied to the booster circuit (13) according to the dissipated current of the liquid crystal drive circuit (14), it is possible to reduce the current dissipation of the booster circuit, that is the current dissipation of the whole booster circuit device can be reduced markedly.
Inventors: | Kawasaki; Masayuki (Ooita, JP); Kuwasima; Yasunori (Ooita, JP); Tachibana; Hidehiko (Ooita, JP); Katsuki; Syuji (Yokohama, JP); Sueda; Akihiro (Yokohama, JP) |
Assignee: | Kabushiki Kaisha Toshiba (Tokyo, JP) |
Appl. No.: | 350353 |
Filed: | December 6, 1994 |
Dec 09, 1993[JP] | 5-309076 |
Current U.S. Class: | 327/538; 327/121; 327/544; 327/589 |
Intern'l Class: | G05F 001/10; G05F 003/02 |
Field of Search: | 327/538,535,536,544,545,589,115,117,121,99,390 345/212 |
3657658 | Apr., 1972 | Kubo | 327/115. |
4883976 | Nov., 1989 | Deane | 327/536. |
4894559 | Jan., 1990 | Kaneko | 327/589. |
5029282 | Jul., 1991 | Ito | 327/536. |
5105187 | Apr., 1992 | Plus et al. | 340/811. |
5362990 | Nov., 1994 | Alvarez et al. | 327/538. |
5388084 | Feb., 1995 | Itoh et al. | 327/538. |